- Author: Barbara Kissinger Santos
My cold season garden is planted with plenty of broccoli and cauliflower. Last week I noticed holes chewed in the leaves. I looked underneath and sure enough, I have cabbage loopers. It's early in the season so only 3 leaves on 2 of my 12 plants are affected, but clearly if I want a decent crop, I'm going to need to be diligent.
What are cabbage loopers and cabbageworms?
Cabbage loopers are a caterpillar that feasts on Cole crops. Cole crops are a group of vegetables that include cabbage, broccoli, cauliflower, Brussel sprouts, collards, and kale. Cabbage loopers are green, up to an inch and a half long, usually with a narrow white stripe on each side and narrow, pale lines down the back. They can be distinguished from other caterpillars that feed on cole crops, such as the imported cabbageworm, by their looping movement. They move by arching the middle portion of their body, pulling the rear end forward and then propelling the front end forward. Imported cabbageworms are smaller, have a hairier appearance and often have one faint yellow orange stripe down their backs.
The caterpillar form of the cabbage looper moth is mottled brown or gray color. These moths lay single eggs on the underside of older cole crop leaves. The caterpillars emerge to eat leaves, mostly mature foliage, and eventually spin a cocoon on the underside of mature leaves, in the crown of the plant or in debris on the ground. The moths emerge to repeat the life cycle. Imported cabbageworms are the caterpillar form of the imported cabbageworm butterfly, a white butterfly with one or more black spots on each wing. They have a similar lifecycle to cabbage loopers.
So What's the Problem?
Cabbage loopers and imported cabbageworms eat leaves and will bore holes in developing cabbage, cauliflower, broccoli and lettuce damaging the fruit of cole crops and leaving their bodies and frass (or insect poop). Newly planted vegetable garden plants can disappear quickly if caterpillars aren't controlled.
How Do I Control Them?
You can prevent these pests from laying eggs by using floating row covers. If you can't do this, examine plants with leaf damage and pick off caterpillars before they do more damage. If you can't find the caterpillars, look for their frass. Stand still, looking slowly around at your plants, giving special attention to the undersides of the leaves.
If you do this diligently, it may be all you need to do. There may be natural enemies such as parasitic wasps or tachinid flies present in your garden to help reduce pest numbers. If these methods aren't sufficient, you can use a less toxic pesticide called BT or Bacillus thuringiensis. Although this product is organic, always follow directions regarding dosage, when to apply, and safety protocols. For more information visit the following UC IPM pages.
For more information, visit the following UC IPM webpages:
Cabbage loopers https://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/loopers.html
Imported cabbageworm https://ipm.ucanr.edu/PMG/GARDEN/VEGES/PESTS/importcabwrm.html
Parasites of insect pests https://ipm.ucanr.edu/QT/parasitesinsectcard.html
Barbara Kissinger Santos has been a UC Cooperative Extension Master Gardener in Stanislaus County since 2024.
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Learn about planting leafy vegetables like lettuce and spinach, and root vegetables like carrots, beets and radishes. Not to mention broccoli and cauliflower. All of these vegetable plants can be grown in the ground or in containers. Great class for beginning gardeners.
We are excited to say that our classes are at nine Stanislaus County Library Branches! We hope to see you there.
August 2023 Library Branch Schedule
- Tuesday, 8/1 at 6:00 p.m. - Salida
- Saturday, 8/5 at 2:00 p.m. - Empire
- Tuesday, 8/8 at 6:00 p.m. - Oakdale
- Thursday, 8/10 at 1:00 p.m. - Patterson
- Saturday, 8/12 at 2:00 p.m. – Riverbank
- Monday, 8/14 at 6:00 p.m. – Ceres
- Tuesday, 8/22 at 2:00 p.m. - Waterford
- Wednesday, 8/23 at 6:00 p.m. - Turlock
- Monday, 8/28 at 5:30 p.m. - Modesto

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As a gardener, I get really excited to plant some of my favorite foods. Broccoli, cauliflower, swiss chard, kale, and lettuce always grace my table each fall and into the winter months. Carrots and sugar snap peas greet me next to my front door. Green and purple cabbage have even lined my walkway tempting me with thoughts of the sauerkraut that will be made from their crunchy heads.
While the majority of my experience has been with planting my veggies in raised beds and in ground, when I was first starting out on my gardening venture I planted several varieties in pots and containers. Lettuce, carrots, sugar snap peas, have all grown well for me in containers.
The best thing about growing lettuce, especially romaine, is that you can harvest the lettuce throughout out the season. By snipping off the older, outer leaves, you can keep your lettuce growing and extend your harvest. I usually sow my seeds every two weeks just to make sure I have lettuce all fall and winter long.
Sugar snap and snow peas are great for containers. I've normally use transplants from the nursery but seeds will work just as well. Choose a container that is quite sturdy as these peas like to have a trellis to grow upon. Place a homemade trellis in the pot and place your transplants or seeds about two inches away from the trellis. Alternately, I have placed my peas in pot next to a pretty trellis leaning against the garage wall and they have loved it. The best thing about growing peas is the more you harvest, the more they produce.
Carrots, for me, are a little trickier. First time I tried them the container wasn't deep enough and I had these little stunted carrots. Choosing a deep container or pot, at least 12” led to better success and a very tasty treat. Remember to thin out your carrots as well or you'll have some very interestingly shaped and twined carrots. They are still edible, but don't look very pretty.
Yes, fall is one of my favorite times of year. Not just for the weather, but for the abundance of produce that we can grow here in the Central Valley. Fall veggie container gardening is a great way to get started on your adventures in gardening.
Terry will be co-teaching our upcoming Fall Vegetable Gardening class on August 25. Save the date! More details coming soon.